In the picture above, notice the
small wall immediately behind the moat. Known as a "sheep-horse" wall,
it created a space in front of the main walls where animals could be corralled
when the area around a city was evacuated. It was also another
barrier to attacks.

Cities isolated on a plain were less vulnerable
than ones in rougher terrain, where the enemy would have more places to
hide and rocks offered ammunition for catapults. When an attack
seemed likely, one defensive measure was to evacuate nearby residents, both to protect them
and to protect the city against the possibility that they might reveal information to enemy
forces.

This illustration of the enemy attacking a fortification is from a novel,
The Water Margin.

What kinds of weapons do you think would have been the most effective in
the circumstances depicted? Do you see them being
used in this image?

Defenders would also generally clear a space around the city to
gain an open view of an approaching army's
activities, and at the same time deny the enemy
access to firewood, ammunition, or cover. This sometimes meant that the
enemy would run out of food, firewood or fodder long before a
well-stocked city would exhaust its supplies.

One of the ways to begin defending a city was to send out troops to attack an encroaching army before it got to the walls, as seen in the illustrations below from the novel, Romance of the Three Kingdoms.
After a siege was well under way, garrisons often mounted sorties outside
the walls to destroy enemy siege engines or supplies and raise morale
within the city.

After surrounding a city, attackers would begin by
delivering leaflets via arrows to explain the consequences of resistance
or the rewards to be given to those who surrendered. When that failed,
as it usually did, the attackers would bombard the city with crossbows
and catapults, then attempt to scale the walls. They would bring in equipment such as bridges, ladders, carts, and
towers, many on wheels, to help in breaching the walls. The illustrations below show six types of tools from The Essentials of Military Arts and The Water Margin.

From
the pictures below, can you guess why city officials would have had plenty of
time to prepare for the attack of an oncoming army?

At left is a "cloud-ladder" from The Essentials of the Military Arts. Scaling ladders were already being used in the Warring States period.

The "fork" cart
to the right, another movable weapon, would
have been used by the attackers to chop at the walls. The pivoting beam
terminating in long claws would sometimes have been attached to a long
ladder for extra height. When a wall's integrity was breached, other
implements such as "buildings in the void,"
"flying ladders" and "cloud ladders" would be moved into
the holes thus created to allow invaders access beyond the walls.

Can you see from the picture how the bridge would have worked? How vulnerable was it?

Other
types of bridges included revolving bridges, connected underground to a
mechanism inside the gates. When the connecting pin was disengaged, the
bridge would turn over and anyone on the bridge would fall into the
moat.

An early version of the tank, at the right, had a rigid spine and was
covered like a tent with oxhide. It was designed to protect men as
they were brought close to the wall. Incendiary arrows could be shot at
the cart, but
if the oxhide was fresh enough, it provided some protection.

In
the eventuality that the gates failed to hold, defenders would have implements such as the one on
the right, a "knife cart for blocking up gates," to roll into place.

When a city did fall, civilians were encouraged to flee, but soldiers
were expected to stay and fight. The sack of a city was usually gruesome,
with indiscriminate slaughter and desperate attempts to buy mercy.